I'm a bit behind on my reading--just got to the October issue of Scientific American.
On page 53, there is an article on artificial muscles, which are made by placing an electrode on each side of an elastomer sheet. Voltage across the electrodes cause the elastomer to change dimensions. Okay...so what? Well, on page 57, they show a membrane which goes from flat to dome-shaped with the application of voltage. On the next page, they offer some information specifically on applying this to loudspeaker construction. They note that mid-range and high frequency drivers have already been made, and that there is no reason why a woofer could not be constructed using the same technology. They cite the mid-range and tweeters as offering 'good performance,' although there's no way of telling whether that's in comparison to a boom box or a high end system.
A few points to note:
--There are both low and high voltage versions of this technology. In the picture, they show the membrane being actuated by a 5kV supply. Tubes, anyone?
Don't panic, Rodd, they mention lower voltages earlier in the article--in the single digit range.
--The construction is basically that of a capacitor. They don't mention any numbers as to whether we're talking pF, uF, F...
--How close drivers are to market, they do not say, but they're already trying to get some other applications out the door. It could be that we might see the first drivers in the next year or two.
--Reliability could be a problem. Or maybe not. They mention breakdown of the membranes if you exceed a given voltage, but, hey, it's not as though current technologies have infinite capability to take abuse.
Just don't be surprised when it shows up at Madisound, Parts Express, et. al.

Sounds great, although it seems remarkably similar to piezoelectric film. I bought one of those samples years ago, and got very little sound out of a 3in by 5in sheet-even the high frequency sound was not coming through with much volume.

Let's see how this one pans out. I'd like to see things move forward, especially in the direction of square diaphragms.

Personally, I think someone who wants to tool up and make 1" and 2" electrostatic squares with rigid, resonance-free electrodes, ready to add in line source arrays or in large rectangular arrangements, might find himself with a lot of customers.

But maybe this new material is the way to go.

PS: Grey, great to see you back on the Loudspeaker forum!

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kelticwizard,
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They do some comparisons with piezo stuff. I've moved on to the November issue, so I don't have the article at hand at the moment. The impression I got was that there were orders of magnitude difference in the movement you could get, i.e. the elastomer critters would be more efficient. The picture shows a circular membrane an inch to two inches in diameter with perhaps a quarter-inch (maybe more) displacement. Not the kind of thing I've ever seen piezos do. Care to imagine the excursion you could get from a woofer panel? And no pesky electrostat/magnetic planar screens to get in the way, either...just the membrane itself.
Being synthetic materials, you could make any size and shape driver you wanted, I imagine.
Perhaps I ought to revamp my old Magneplanars with this stuff. On the other hand, eighteen inches of displacement might be a little intimidating!
Ken,
(Got a step-kid up there at Clemson.)
Manger...dunno. I read up on them at one point, but the particulars escape me at the moment, so I can't contrast and compare. If I get time, I'll try to scrounge around and refresh my memory on the Manger. Isn't the Manger a rigid piston that depends on breakup for higher freqencies? This thing's flexible. That'd be one difference.
Given that the October issue is almost certainly off the stands, you'd probably have to find it at a library, unless you happen to have a subscription and happened to miss the article. Pretty cool stuff, though.

One driver that is made of a piezoelctric polymer is a tweeter by Audax that got good reviews. It uses an "air cored" step up x-former.
Unfortunately it isn' t made anymore but there may be some stocks left.

There were also speakers made by Pioneer in the seventies using piezo polymer tweeters.

Originally posted by phase_accurate One driver that is made of a piezoelctric polymer is a tweeter by Audax that got good reviews. It uses an "air cored" step up x-former.
Unfortunately it isn' t made anymore but there may be some stocks left.

There were also speakers made by Pioneer in the seventies using piezo polymer tweeters.

Originally posted by panzk ......the technology now is rather perfect, any new innovation will not be easy.

Perhaps a better way of putting this might be...

Current technology now is rather mature, and that innovations are more likely to come from newer technologies that are still in their infancy, and may be a long time coming.

Twenty years ago, no one had ever heard of a digitial amp much less a digital crossover and now they are available as consumer items at consumer prices. Wtih growing pains to be sure, but still they have a certain amount of market penetration at a consumer level.

Such things as the speaker technologies that Grey is posting about, the Bucky tubes nanotechnology, these and other new technologies hold a lot of promise.

What am I saying??? I'm a died in the wool tube guy!!

regards

Ken L

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